Aircraft landing gear



Oct. 8, 1946. R. P. MURDOCH AIRCRAFT Lunma GEAR Filed April 12. 1943 @fiented Get. 8. i946 AIRCRAFT LANDING GEAR Robert P. Murdoch, Mount Lebanon, Pa.

I Application April 12, 1943, Serial No. 482,686 I 1 Claim. 1

This invention relates to new and useful improvements aircraft landing gear, and it is among the objects thereof to provide means for rotatin the wheels of aircraft preparatory to landing to avoid the abrasive action of the ground surface on the wheels resulting if the wheels are static.

It has heretofore been proposed to utilize vanes on the wheels of airplanes, which will rotate the wheels in response to the air flow when the landlng gear is dropped prior to landing. An obvious disadvantage of this type of actuator is the added resistance or load in the take-oil as the wheels cannot be immediately retracted until the ship has reached a sale altitude.

In accordance with the present invention, means are provided to positively drive the wheels by a prime mover contained within the wheel housing or mounted on the wheel carriage, thereby ordering no resistance to the normal flight of the plane. I

The invention further contemplates a motor drive which shall maintain positive contact with the wheel at all times so that the wheels may be positively rotated when the landing gear is in its fully extended position.

A further object of the invention is the provislon of a motor drive which shall be capable of revolving the land ng wheels at approrlmately the landing speed of the plane, and still a further object of the invention is'tlie provision of means for automatically energizing the motor circuit when the carriage has been extended to landing position, and to automatically disconnect the mo from the power circuit when the plane is landed.

These and other objects oi the invention will become more apparent from a consideration oi the accompanying drawing constituting a part her-sci in which like reference characters desig= note like parts, and in which:

Fig. l is a iront elevaticnal view of an airplane motor housing partially cut away, showing the landing gear embodying the principles of this invention:

Fig. 2 a top plan view of the wheel drive and a portion of the wheel carriage; and

The invention does not involve the operating mechanism forthe wheel carriage, which is therefore not shown. Mounted on the carriage frame 4 is a friction drive wheel 8 rotatable by a shaft 9 of an electric motor ill, the shaft 9 being biased by springs 9 so that the friction wheel 8 is at all times in contact with the outer periphery of the landing wheel 2 to be capable of rotating the latter when it is free and off the ground.

10 The arm 6 of the toggle is split and'provided with a shock absorber H which may he of the spring or pneumatic type, or both, in which a piston member It operates in a cylinder is. The cylinder is provided with an electrical contact it which constitutes a terminal in the circuit of motor l0, and the piston i2 is provided with the spring biased contact i5 which also constitutes a terminal of the circuit of motor ill.

Contacts M and it are shown separated in the go position of the shock absorber in Fig. 3, which is the position of same in the retracted position of the landin gear.

In Fig. 4 when the links 5 and t of the toggle are vertical, the piston 32 is displaced to the po= g5 sition where terminals i l and 95 contact to energize the drive motor it), and in Fig. 5 the ter minals It and B5 are separated'by the weight of the plane on the landing gear after the plane is landed. In this position, the motor circuit is 39 broken and the drive motor itstops.

To control rotation of the landing wheels 2' to proximate the speed of the wheels at the normal landing speed of the plane, the drive motor ii) is wound as a constant speed torque motor, devel=- g5 oping a. maximum speed corresponding to the pe ripheral speed of the wheels at the landing speed of the plane. When the carriage is lowered, which establishes the power circuit for the drive motor it], it will rotate at slow speed while developing to the torque needed to rotate wheel 2 and gradually bring it up to the landing speed which is the maximum speed of the motor it.

Although one embodiment of the invention has been herein illustrated and described, it will be evident to those skilled in the art that various Figs. 3, 4 and 5 vertical cross-secticnalviews of a shock absorber on the wheel carriage having electrical contacts therein.

With reference to. the several figures of the drawing, the numeral i designates the engine nacelle, having the landing gear mounted on one side thereof, the landing gear comprising the indated rubber tires or wheels 2 journalled on axle mounted on the carriage generally designated by the numeral 6, The carriage is provided with links 5 and S pivoted at l and to the wheel axle 3,, and are shown in the retracted position, the links being a toggle which forms a straight vertical strut when the wheel carriage is dropped.

modifications may be made in the details of construction without departing from the principles herein set forth.

I claim: I

59 In combination with a landing gear and landing wheels for aircraft, a positive drive for said wheel comprising a friction wheel in contact with the outer periphery of the landing wheel, an elec'-.

tric motor for driving said friction wheel, and

means responsive to movement of the landin gear to its extended position for energizing said motor and for deenergizin the motor circuit by I the impact of the landing wheel with the ground. 

